Method of making sheet metal



March 13, 1945. R Aus'm 2,371,124

METHODS OF MAKING A SHEET METAL BUILDING UNIT Filed June '17, .1942

INVENTORS I ATTORNEYS chem. ,Ausfin. Geprge uncombml:

Patented Mar. 13, 1945 METHOD OF MAKING SHEET METAL BUILD NG UNITS Chester R. Austin and c eorge lL-Duncombe, Jr.,

Columbus, Ohio, 'assignors, bymesne assignments, to Davidson Enamel Products, Inc.,

' Lima, Ohio, a corporatio n of Ohio Original application August 4, 1940, Serial No.

351,334. Divided an 1942, Serial No. 447,456

8 Claims.

I This invention relates to methods of making a sheet metal building unit. It relates particularly to a method of making enameled metal sheets or tiles designed for architectural and structural purposes, although it is not necessarily limited thereto.

This application is a division of our co-pending application Serial No. 351,334, filed August 4, .1940.

Enameled sheet metal tiles or construction units of this general type have long been known to the art. Their use has been desirable because they are light and strong, comparatively inexpensive andeasily assembled. Usually, they have taken the form of shallow sheet metal pans of any desired size and shape. It has been customary to apply the completed unit to a wall or d this application June 17.

' surface, the prior art has been deficient in prosound hollow" or "tinny."

other surface and, in many cases, backings have a been formed in each pan either prior to assembly or after mounting of the unit in place.

.In the making of enameled units of this type, considerable difliculty has arisen because the firing of the enamel on the pan or tile resulted in warpage thereof. Such warpage produces a tile of uneven surface which, for many services, is highly undesirable as when several of these units are mounted together in a. wall. The surface irregularities resulting from the warpage are intensifled by the light reflective character of the enameled surfaces and even relatively small depressions or elevations in the outside surfaces of the units are thus easily seen.

One prior art method of overcoming this difficulty has been to make the metal tile, tray or pan of heavier metal than needed in the unit merely so that it would hold its shape better on firing. This device has brought about'some improvement but has resulted in an increase in the cost of the metal requiredand, consequently, of the finished tile.

Another method proposed in the prior art has been to provide minor corrugations, bosses or protuberances in the flat surface of the tile to increase its resistance to sagging or warping. To

be efl'ective, however, these had to be so big thatv undesirable surface efiects resulted and made these units unsatisfactory where a practically fiat wall surface was desired.

In still another prior art method, the front face of the tile was given a permanent outward bow as formed and was provided with a flange around its edges so that this tile would hold its shape during firing. This produced a tile with a slightly convex surface and for many services resulted in an undesirable wall surface.

All of these prior art methods have been unduclng a metal tile unit which would have a solid sound when struck and which would not A solid sounding tile is desirable and the best prior art solution of this problem has apparently consisted in the use of some sort of a backing material which would give a solid sound to the unit, since it seems obvious that an unbac'ked enameled metal unit will always have a hollow," metallic sound when struck. In order to overcome this difliculty, sheet metal tiles have often been backed with mortar, cement or plaster but considerable difliculty has been experienced in obtaining good adhesion between the backing materials and the tiles. With this type of structure, the enameled metal sheet has a tendency to break away from the backing, at least in certain spots, so that the backing could no longer efficiently perform its proper functions. It has also been found that if the backing and the metal sheet are not actually bonded, satisfactory results could not be obtained, from the standpoint of sound, even though the backing and sheet metal are in intimate contact.

To improve this bonding, anchoring devices, lugs, pins and fingers have been Welded, riveted or soldered to. the sheet metal tile. They provide a firm anchorage at the point wher the device is used but it is obviously not feasible to use a large enough number of these elements to anchor the tile completely to its backing material and, unless these elements are very closely spaced,

' portions of the enameled metal and its backing may separate in the space between the fasteners. Even if such separation does not occur, the sound of the tile when struck is not as good as is desired. Hence there is considerable need for a method to bond the backing material firmly to the enameled metal surface in some, uniform manner over the whole area of contact.

One of the objects of this invention is to provide a method of making a sheet metal tile which will be lightand strong, comparatively inexpensive and easilyv assembled and which will be substantially free from surface irregularities, whether itbe enameled or not.

Another object of this invention is to provide a method of making a sheet metal tile formed of relatively light metal without corrugations, bosses or protuberances and which will at the same time permit construction of a practically flat wall surface.

Another object of this invention is to provide a method of making a sheet metal tile which will have a solid sound when struck and will not sound hollow or tinny."

Still another object of this invention is to provide a method of making a sheet metal tile with a backing which will be adequately bonded to the metal without the use of anchoring devices, such as lugs, pins, fingers or the like.

Various other objects of this invention will appear as this description progresses.

The accompanying drawing illustrates our method together with apparatus which may be utilized in making the tile. In this drawing, similar characters of reference designate corresponding parts and in this drawing:

Figure 1 is a perspective view of a sheet metal pan which is shown with blistered enamel on its inner surface to facilitate the bonding action.

Figure 2 is a perspective view of a portion of the metal pan shown in Figure 1.

Figure 3 is a perspective view of an apparatus which may be used in applying a backing material to the interior of the metal pan. I

Figure 4 is a view partially in vertical section of a portion of the apparatus shown in Figure 3.

Figure 5 is a view partially in vertical section illustrating a modified form of our method.

Figure 6 is a perspective view, partially broken away, of the finished product.

In the preferred method of making our enamtac t plates or members l8, which latter have their edges upturned as shown at iii. In other words, the force is applied to the tray or pan by the adjustable plungers 8 and contact plates l8 through the medium of the interposed pieces or blocks IA. The tray may then be filled with the backing material -l 3 in the form of a slurry and in surroundeled sheets, a sheet metal tray I is coated on its I outer surface with a smooth layer'of enamel 2 and on its inner surface with a blistered layer of enamel 3. This tray is then placed on a flat surface 4 of a table 5, with the face of the tray down. Force is then applied to the interior fiat. surface 'of the tray by means of a plurality of screw threaded plunger members 6 provided with handles l and mounted for vertical adjustment in .metal plates 8 which are hinged as at 9 to removable brackets ID that fit upon one end of the 4 table. The opposite ends of these plates 8 are secured as at H to brackets I2 which flt upon the opposite end of the table 5.

With these parts in the position indicated in Figure 3, force is applied by means of the screw threaded plunger members 6 so that the flat portions of these trays are straightened, flattened and forced against the plane surface of the table against which they. rest. While the tray are in this flattened condition, they are filled with a backing material I 3 which sets upon standing. After this backing material sets, the screw threaded plungers which have been used to flatten the tray are released, so that force thereof is removed and the unit i ready for use or for furtherprocessing.

Referring particularly'to Figures 3 and 4 of the drawing, there is shown suitable apparatus for carrying out our improved method of producing a building unit embodying the present invention in which amonolithic backing is provided for the a sheet metal tray. This is accomplished by placing small'pieces orblocks the flattening force ing relation to the small pieces or blocks H of hardened backing material. The slurry of material is then allowed to solidify or set. The pressure is now relieved by releasing the screw threaded plungers 6 so that the force thereof is removed and the unit is ready for use or for further processing. The small pieces or blocks Id of backing material are left in the backing l3 and a truly monolithic backing is obtained.

In accordance with another form of the present invention in which suitable apparatus for carrying it out is shown in Figure 5, frusto-conical plug members or fingers l5 are positioned in spaced relation on the blistered layer of enamel 3. Thereafter, the screw threaded plunger members 5 are adjusted so as to bring their contact plates or members i8 into engagement with the top surfaces of the member i5 to apply a force to the bottom portion of the tray to straighten and flatten said portion by forcing it against the plane surface 4 of the table '5. The tray is then filled with suitable backing material l3 which surrounds the spaced plugs and is allowed to solidify and set. 'After such solidification, the screw threaded plunger members 8 and their contact plates l8 are released from force applying engagement with the plug I5. To facilitate withdrawal of the fingers or plugs l5, they may be coated with a soap solution or other. suitable material to which the backing material will not adhere. The use of the removable plugs or members I5 will leave small holes in the backing material l3 upon their withdrawal, but for many purposes this is not objectionable.

The size and shape of the tray used will depend on the use to which it is to be put. It has been found that rectangular tray 20" x 24" and 24" x 30 are well suited to this purpose. The structure of the blistered enamel back must contain many open blisters so' that the backing material can key into the enameled metal. In addition to being open these blisters should be comparatively large, preferably being larger than /8" in diameter. If too small the surface tension of the backing material might prevent it from entering the blister and keying therein. When small blisters are encountered backing materials of low surface tension may be used but this is not the preferred practice.

The backing material which is poured into the rigidly held tray may be any material in liquid form which is capable of transforming to a solid state in a comparatively short period. Thus, it may be a material such as plaster of Paris, which sets by the addition of water, or a true hydraulic material, such as Portland cement. Likewise, it may be any material which sets or hardens on standing, as, for example, molten pitch, asphalt or sulfur.

It has been-found that after the material sets. is removed .but the backing has. sumcient strengthto hold the tray in its flatteriorate with time.

' tened position,

while the bond between the backing material and the biistered enameled surface is strong and complete and does not tend to de- A unit so backed sound: like a solid piece of material when struck.

The numberv and spacing of the points of application of the flattening force depends on the size and shape of the unit as well as the severity of warping of the enameled tray. Spacing on 8" centers is satisfactory in many cases but closer spacing produced slightly better results. Sixteengage metal is ordinarily used for units of this type but .by this method it is possible to use twentygage metal without diiliculty, which effects a reduction in the weight of metal required. Furthermore, the thinner metal requires less flattening. force in processing.

The superiority of units produced according to this invention may be seen from the following table in which the maximum deviation of the enameled front surface of a unit from a true plane is taken as the measure of the effectiveness of the process:

Table I-Jmprovement in enameled tile surfaces by flattening treatment 1 Average for six different tile.

2 Trade name U. S. Gypsum Co.

3 Average for four different tile.

Thesound produced when these units were struck was not measured numerically but the un-.

backed tile and those not having a blistered enamel layer on their reverse side, even though provided with backing material, had a tinny or hollow sound while the units produced in accordance with this invention had a solid sound like that of glass, marble and similar dense, strong materials.'

The amount of backing material required, in structure and density, and the time required for setting are all functions of the backing material used' With a high strength plaster of Paris, it was found that about /2" thickness of the dense material was required to hold a 24" x "16 ga e enameled tray in straightened position. For the plaster of Paris backings referred to in the table. it was found that 45 minutes was an adequate setting time. l The same amount of plaster can be used with an Y increased amount of cellular space to increase the thermal insulating value of the backing while, at the same time, obtaining the advantages previously described with relation to the more dense material. With plaster of Paris, however, it is desirable that the volume not be increased over 50% of the normalwet-mixed volume or the backing may be undesirably weak.

As is well known to the art, the backing may be reinforced with suitable materials and waterproofed by suitable paints or other coatings. Other appropriate treatments may be given the backing material to secure any desired results.

It will be seen that the method of. this inventionproduces an enameled sheet metal unit for structural purposes which has a practically flat surface and which has the sound of dense solid material when struck. The product is cheap and permanent and may be produced with a variety ofcharacteristics which may be modified to suit the use'to which the unit is to be put.

expensive and easily assembled and which will be for a high strength plaster of Paris marketed by the substantially free from surface irregularities, whether it be enameled or not. Likewise, the tile resulting from our method will have a solid sound when struck and will not sound hollow or tinny." In addition, the backing which we have utilized will be adequately bonded to the metal without the use of anchoring devices, such as lugs. pins, fingers or the like.

Various other advantages will appear from the appended claims.

Having thus described claim is:

1. The method. of producing a sheet metal buildin unit which comprises coating the rear surface of said sheet of metal with blistered enamel, positioning said sheet of metal face downward on a plane surface, applying force to said sheet metal to press it against said plane surface, and applying a backing material thereto during the application of said force.

2. The method of producing an enameled sheet metal building unit which comprises coating the face of said sheet with enamel, coating the rear surface of said sheet of metal with blistered enamel, positioning said sheet of metal face downward on a plane surface, applying force to said sheet metal to press it' against said plane surface and applying a backing material thereto during the application of said force.

our invention, what we 3. The method of producing an enameled sheet mitting said material to solidify during application of said force.

l. The method of producing an enameled sheet metal building unit which comprises coating the face of said sheet with enamel, coating the rear surface of said sheet metal with blistered enamel, positioning said sheet of metal face downward on a plane surface, positioning hardened pieces of laster-like material on the upper surface of said sheet metal, applying force to said hardened pieces of plaster-like materiaL'surrOunding said hardened pieces of plaster-like material with a similar material in liquid or semi-liquid form and permitting said. plaster-like material to set during the application of said force.

5. The method of producing a sheet metal building unit which comprises preparing a sheet metal tray with a blistered enamel surface on its inner surface, placing the tray with its outer face down on a plane surface, flattening the tray by the application of force at a plurality of points. applying a backing material capable of setting on the blistered enamel surface, continuing the application of force until the backing material sets and then removing the force.

6. The method of producing an enameled sheet metal building unit which comprises preparinga sheet metal tray with an enamel surface on its face and a blistered enamel surface on its reverse side, placing the tray, face down, on a plane surface, flattening the tray by the application of force at a plurality of points, applying a backing material capable of setting on the blistered enamel surface, continuing the application of force until the backing material sets and then removing the force.

7. The method of preparing an enameled sheet metal building unit which comprises placing an enameled sheet metal tray, face down, on a plane surface, said tray having a blistered enamel surface on its reverse side, applying force to the blistered enamel surface to flatten the enameled metal tray, said force being applied through a plurality of fingers which bear upon the blistered enamel surface, filling said tray with a material capable, of setting, allowin said material to setand withdrawing the force-applying fingers.

8. The method of preparing an enameled sheet metal building unit which comprises placing an enameled sheet metal tray, face down, on a plane surface, said tray having a blistered enamel surface on its reverse side, applying force to the biistered enamel surface to flatten the enameled.

metal tray, said force being applied through a plurality of members which bear upon inserts resting upon the blistered enamel surface and adapted to remain in the completed unit, filling said tray with a material capable of setting, allowing said material to set, and withdrawing the force-applying members.

CHES'I'ER R. AUSTIN. GEORGE'H. DUNCOIVIBE, Ja. 

